From zedequalszee:

Nomadic Sound Systems: Think marching band, but with bass, mid and treble speakers instead of instruments. Instant dynamic site-specific music piece!

These remind me of Russolo’s intonarumori (substituting speakers for various mechanical contraptions), but even more of this line from Sousa’s “The Menace of Mechanical Music”:

Shall we not expect that when the nation once more sounds its call to arms and the gallant regiment marches forth, there will be no majestic drum major, no serried ranks of sonorous trombones, no glittering array of brass, no rolling of drums? In their stead will be a huge phonograph, mounted on a 100 H. P. automobile, grinding out “The Girl I left Behind Me,” “Dixie,” and “The Stars and Stripes Forever.”